You sure you can jump out of it ? Have tried it in the past and got hit. On a second thought i might not have jumped fast enough.
you jump out in the direction the reptile is dashing at you because then it becomes a jump out backwards using taht input.
reptile - you
in this setup you would perform a Up, Left jump the second you see the ex dash. Do not wait, your human reaction to seeing the ex dash start is slow enough that if you make a blind leap of faith, you do in fact jump out.
Make sure you kick it seems to help the hit box and avoid being hit.